①÷12÷
②×÷
③÷÷
④××
⑤÷÷
⑥÷×
1400×(1+12%)
24÷(1-60%)÷
÷25%+4×
5.6×(480%-480%÷150%)
①(x+)=2.4 ②1.1x-0.4=7.2×
2.1÷ = × = 52×79≈ 2.5×7.8×0.4=